This invention relates to wheel covers for motor vehicle road wheels and to an assembly comprising such wheel covers mounted to a wheel.
Numerous retention means and systems are known to the skilled of the art for retaining a wheel cover to a motor vehicle wheel. It frequently is desirable to provide a wheel cover with a retention system which does not rely on any particular contour of the wheel's surface to retain the wheel cover in position. Wheel cover retention means which rely on a frictional engagement with a radially inward facing annular surface of the rim portion of a wheel or the lip flange of such rim portion are known. Such retention means, generally located at the outer periphery of the wheel cover, do not positively lock the wheel cover to the wheel and, in addition, typically prevent rotation of the wheel cover outer periphery relative to the vehicle wheel. Also, such peripheral retention means involve considerable manufacturing complexity and cost, typically requiring the use of metal bands, metal retention clips, etc. Also, the wheel cover must be of adequate weight and structure to afford a durability requisite to withstand the forces applied to the wheel cover to engage it with the vehicle wheel periphery.
Other wheel cover retention systems are known which rely on the lug stud nuts which retain the wheel to the vehicle axle. Such systems, however, generally require the use of a non-standard lug stud nut adapted to facilitate such engagement with the wheel cover. This presents both a cost and complexity penalty for such retention systems. In addition, retention means of this type typically are disadvantageous in that the vehicle wheel must be mounted onto the lug studs and held in position without benefit of the lug stud nuts while the much more fragile wheel cover is mounted over it onto the lug studs. Not only is this frequently a difficult operation to coordinate, but it presents risk of damage to the fragile wheel cover while the lug stud nuts are assembled, because during this time the heavy wheel cover is held in position by applying considerable pressure against the outer surface of the wheel cover. One such system of this type employs a so-called bulge-nut type of lug stud nut. Specifically, a wheel cover according to this system provides circumferentially spaced apertures to receive the vehicle wheel lug studs. A lug stud nut with a decorative cap, such as a bright chrome plated cap, covering the axially outward end thereof would be applied to hold both the wheel cover to the wheel and the wheel to the axle hub. Such lug stud nuts have an annular bulge axially inward of the cap, whereby an annular recess is defined between the bulge and the inboard end of the cap. A washer, typically a split ring type, would be trapped in the annular recess. The bulge would fit through the circumferentially spaced apertures in the wheel cover to sea-t against the vehicle wheel; the trapped ring would not fit through the wheel cover aperture but, rather, would seat against the outboard surface of the wheel cover peripheral to such aperture and thereby hold the wheel cover against the wheel. As noted above, this type of retention system is significantly disadvantaged in that the special lug stud nuts, i.e. the bulge nuts, involve a considerable cost disadvantage. It is disadvantaged also in that the need to mount the wheel cover to the wheel prior to securing the wheel by the lug stud nuts is a complex and difficult operation both for the vehicle manufacturer and, subsequently, for the vehicle owner or others doing work requiring removal and reinstallation of the vehicle wheel.
It is an object of the present invention to provide a wheel cover and a wheel cover assembly employing a retention means which does not require engagement with the vehicle wheel at the outer periphery of the wheel cover and which does not require non-standard lug studs or lug stud nuts. It is a further object of this invention to provide a wheel cover with a retention means, whereby such wheel cover can be mounted separately and independently to the vehicle wheel at a time following mounting of the wheel to the axle hub. Additional objects and advantages of the invention will be understood from the following description.